This invention relates generally to a bandage for a chest wound and more specifically relates to a bandage device and method for covering an open chest wound.
Normally, when the chest expands and the diaphragm contracts, a negative pressure is developed inside the chest cavity. Air then rushes into the chest cavity from the upper airways and the trachea and expands the lungs. When the diaphragm and chest relax, a positive pressure is developed inside the lungs that force the air out from the lungs, through the trachea and discharged to the outside via the upper airways.
If a victim is wounded in the chest from a knife or bullet, causing a substantial opening in the chest cavity which is large enough to remain open, air will enter and exit the chest cavity through the wound opening in response to changes in the thoracic pressure. The air entering the thoracic cavity through the wound will only flow within the pleural space and will not enter the lungs, thereby eventually causing the chest to suck inward and the lungs to collapse.
If the wound opening is larger than the glottic or trachea opening, more air will enter the pleural space from the outside than will flow into the lungs from the upper airways. Thus, more air accumulates in the pleural space than within the lung parenchyma. Eventually this leads to hypoxia of the lungs, due to decreased exposure of lung tissue to oxygen.
Moreover, if the chest wound includes a flap, the air may become trapped, creating a tension force in the thorax which inhibits air inspiration into the lungs. The effect of this also causes hypoxia of the lungs.
Therefore, the air flow into the pleural space from the wound opening incapacitates the diaphragm so that it is unable to form a negative pressure to ventilate the lungs, and the wounded person will smother in the same manner as if the airways into the lungs were obstructed (but in this instance the airways into the lungs could be perfectly clear and unobstructed).
To treat the open wound leading into the pleural space and prevent the chest from sucking inward, the wound should be covered to close the chest opening from air flowing into the chest cavity. Prior to the invention herein, Saran wrap (a trademark to identify a thin plastic membraneous sheet material used to cover foods) having the property of clinging to materials, was suggested to be used to cover and close the open chest wound. Also a gel defibrillator pad or petroleum or VASELINE (Vaseline is a registered trademark identifying a product sold by Chesebrough Ponds Inc.) gauze were recommended to be used to cover the open wound and prevent pneumothorax from occurring. However, these procedures did not provide an exit path for discharging fluids from inside the chest cavity to the outside.
For a small opening chest wound, it was also suggested that the open end of a condom could be taped over the wound and the closed tip of the condom cut off to permit exiting of air from inside the chest cavity. For a larger opening chest wound, a plastic or rubber glove could be used to cover the wound opening and cutting off a tip from one of the fingers to provide an air exit.
The problems with the foregoing proposed solutions were that the opening made in the condom or the glove finger may be too large and cause substantial back flow of air into the chest cavity and prevent ventillation of the lungs; or that such opening may be too small and prevent sufficient discharge of the air or liquid pressure being built up in th chest cavity.
In U.S. Pat. No. 4,541,426 WEBSTER (1985), a dressing is disclosed for application over lesions of the skin, including a first layer formed of material which swells in contact with liquid and a second layer which does not swell or swells less than the first layer when in contact with liquid. Slits shaped apertures are formed in the layers and normally are closed when dry and open when liquid flows into the layers. The WEBSTER dressing appears to be usable for closing a chest wound, but it doesn't provide an opening for air to flow to the outside for removing the pressure on the lungs.
Therefore, a primary object of this invention is to provide a chest bandage and method to close an open chest wound and to release the fluids accumulated inside the chest cavity to the outside.
Another object is to provide a bandage for covering an open chest wound and inhibiting air flow through the wound opening from the outside but providing an exit pathway through the wound opening for discharging air or liquid from inside the chest cavity to the outside.
A primary feature of this invention is to provide a bandage having a normally closed valve for closing an open chest wound, and the valve opens in response to the force from air or liquid flowing into the valve from inside the chest cavity, for releasing such air or liquid to the outside. A further feature is that the valve automatically closes when the air or liquid flow or pressure into the valve from inside the chest cavity is substantially reduced or ceases.
A further feature is to provide a bandage having a valved section formed into an angled configuration to provide optimum drainage of fluids from inside the chest cavity to the outside.